Take your old breaker with you to Lowes, that is where I purchased 2 breakers to fill the 2 expansion slots. I installed a (2) 15 amp mini breaker in each of the 2 expansion slots and wired TT's battery charge controller to it so it would not operate while on SOLAR.. ( has been in the off position for the last 4 years). I would think that your panel should use the same ones.
Square D has one also but not sure of the model number
It has the 2 15 amp mini-breakers on it.
2013 Jayco Eagle 284BHS
250Watt Grape Solar Panel, MorningStar MPPT 60 Charge Controller
1500 Watt Ramsond PSI, 2 Trojan T145 Batteries (260Ah)
2 - AirSight Wireless IP Cameras (used as rear view cameras)
EnGenius WI-FI extender, D-Link wireless (n) modem
MagicJack Internet Phone
2012 Ford F150XLT, EcoBoost w/3.73
157" Wheel base, HD Towing Package
Our Solar Album http://www.jaycoowners.com/album.php?albumid=329